Heat exchanger

ABSTRACT

The present invention relates to a heat exchanger applied to a boiler, and an object of the present invention is to provide a heat exchanger that can improve heat transfer efficiency by reducing distance between the heat exchange pipes while making a heating water passage passing through heat exchange pipes be long, and can be easily manufactured. In order to achieve the heat exchanger, according to the present invention, heat exchanger includes a heat exchange device, first and second subsidiary plates, and first and second end plates. The heat exchange device includes a plurality of heat exchange pipe units through which heating water passes and which are spaced apart from each other at regular intervals, and the heat exchange pipe units are provided between a heating water inlet and a heating water outlet, and are formed of pipes having a rectangular cross-section of which a side coming in contact with the combustion gas has a width large than the height. The first and second subsidiary plates are fixed to both ends of the heat exchange pipe units in order to maintain a distance between the plurality of heat exchange pipe units constant. The first and second end plates are fixed to the outer surfaces of the first and second subsidiary plates, respectively.

TECHNICAL FIELD

The present invention relates to a heat exchanger applied to a boiler, and more particularly, to a heat exchanger where heat transfer is efficiently performed between heating water passing through heat exchange pipes and exhaust gas.

BACKGROUND ART

Examples of a combustion device, which can heat heating water flowing through a heat exchange pipe in a combustion chamber by using a burner as widely known, may generally include a boiler, a water heater, and the like.

That is, boilers, which are used in houses or public buildings, are used for heating or hot water. The water heater is used to quickly heat cold water at a predetermined temperature in order to allow a user to conveniently use hot water.

The combustion device, such as the boiler and the water heater, includes a system that generally uses oil or gas as fuel and burns the fuel by a burner, heats water by using the heat of combustion generated in the combustion process, and provides the heated water (hot water) according to user's needs.

The combustion device is provided with a heat exchanger so as to absorb the heat of combustion generated from a burner. Various method of improving the heat transfer efficiency of the heat exchanger has been proposed in the related art.

FIG. 1 is a schematic front view showing the structure of a heat exchanger in the related art, FIG. 2A is a detailed cross-sectional view taken along a line A-A of FIG. 1, and FIG. 2B is a detailed cross-sectional view taken along a line B-B of FIG. 1.

Referring to FIGS. 1 and 2, a heat exchanger 1 includes a heating water inlet 10, a heat exchange device 20, and a heating water outlet 30. Heating water flows through the heating water inlet. The heat exchange device includes a plurality of heat exchange pipes 21, 22, 23, 24, and 25. The surfaces of the heat exchange pipes come in contact with combustion gas so that heat transfer is performed while heating water flowing from the heating water inlet 10 passes through the heat exchange pipes. The heating water, which is heated while passing through the heat exchange pipes 21, 22, 23, 24, and 25, is discharged through the heating water outlet.

The heating water inlet 10 and the heat exchange pipes 21, 22, 23, 24, and 25, are connected to each other by pipe connectors 11. The heating water outlet 30 and the heat exchange pipes 21, 22, 23, 24, and 25 are connected to each other by pipe connectors 31.

Each of the heat exchange pipes 21, 22, 23, 24, and 25 has a substantially rectangular shape that has a large width and a small height in a longitudinal direction where combustion gas flows. The heat exchange pipes 21, 22, 23, 24, and 25 are spaced from each other by a predetermined distance, so that heat transfer is performed while the combustion gas passes between the heat exchange pipes 21, 22, 23, 24, and 25.

The heat exchange pipes 21, 22, 23, 24, and 25 includes upper plates 21 a, 22 a, 23 a, 24 a, and 25 a and lower plates 21 b, 22 b, 23 b, 24 b, and 25 b, respectively. The upper plates 21 a, 22 a, 23 a, 24 a, and 25 a and the lower plates 21 b, 22 b, 23 b, 24 b, and 25 b are fixed to each other at flanges thereof by welding.

Further, each of the pipe connectors 31, which connect the heat exchange pipes 21, 22, 23, 24, and 25, includes first and second connecting members 31 a and 31 b that have flanges bent in a lateral direction and are fixed to each other by welding (the pipe connectors 11 at the entrance of the heating water have the same structure).

DISCLOSURE OF INVENTION Technical Problem

However, in the heat exchanger having the above-mentioned structure, a distance between the heat exchange pipes is large due to the structural characteristic of the heat exchange pipes that include the upper and lower plates and first and second connecting members. For this reason, there is a drawback in that heat transfer efficiency deteriorates. Further, there are problems in that it is difficult to actually apply the heat exchanger to a boiler because the manufacture of the heat exchanger is complicated and difficult.

Technical Solution

The present invention has been made to solve the above-mentioned-problem, and an object of the present invention is to provide a heat exchanger that can improve heat transfer efficiency by reducing distance between the heat exchange pipes while making the heating water passage passing through the heat exchange pipes be long, and can be easily manufactured.

In order to achieve the above-mentioned object, according to an aspect of the present invention, a heat exchanger includes a heat exchange device, first and second subsidiary plates, and first and second end plates. The heat exchange device includes a plurality of heat exchange pipe units through which heating water passes and which are spaced apart from each other at regular intervals. The heat exchange pipe units are provided between a heating water inlet and a heating water outlet, and are formed of pipes having a rectangular cross-section of which a side coming in contact with the combustion gas has a width large than a height. The first and second subsidiary plates are fixed to both ends of the heat exchange pipe units in order to maintain a distance between the plurality of heat exchange pipe units constant. The first and second end plates are fixed to the outer surfaces of the first and second subsidiary plates, respectively.

In this case, pipe insertion holes may be formed through the first and second subsidiary plates in a longitudinal direction of the first and second subsidiary plates. Both ends of the plurality of heat exchange pipe units may be fitted into the pipe insertion holes. Both ends of the heat exchange pipe units, first and second subsidiary plates, and first and second end plates may be fixed by brazing welding, respectively.

Further, the plurality of heat exchange pipe units may form a series of flow passages of which flow directions are alternately changed in opposite directions while the heating water, which flows from the heat exchange pipe unit provided at one end, flows to the heat exchange pipe unit provided at the other end in opposite directions.

In this case, the heating water inlet may be formed through the first end plate, and the heating water outlet may be formed through the second end plate.

Furthermore, the heating water inlet may be formed on the outer surface of the heat exchange pipe unit into which heating water flows, and the heating water outlet may be formed on the outer surface of the heat exchange pipe unit from which heating water flows.

Meanwhile, the cross-sections of the plurality of heat exchange pipes may be formed so that a distance between the heat exchange pipes at the entrance of the combustion gas is large and a distance between the heat exchange pipes at the exit of the combustion gas is small.

ADVANTAGEOUS EFFECTS

As described in detail above, in the heat exchanger according to the present invention, it is possible to obtain advantages of improving heat transfer efficiency by reducing a distance between the heat exchange pipes while making the flow passage passing through the heat exchange pipes be long, and being easily manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view showing the structure of a heat exchanger in the related art;

FIG. 2A is a detailed cross-sectional view taken along a line A-A of FIG. 1;

FIG. 2B is a detailed cross-sectional view taken along a line B-B of FIG. 1;

FIG. 3 is an assembled perspective view of a heat exchanger according to an embodiment of the present invention;

FIG. 4 is an exploded perspective view of the heat exchanger shown in FIG. 3;

FIG. 5 is a cross-sectional view showing heating water passages of the heat exchanger shown in FIG. 3;

FIG. 6 is an assembled perspective view of a heat exchanger according to another embodiment of the present invention;

FIG. 7 is a cross-sectional view showing heating water passages of the heat exchanger shown in FIG. 6;

FIG. 8 is a cross-sectional view of pipes of the heat exchange according to another embodiment of the present invention; and

FIG. 9 is a cross-sectional view of a heat exchange pipe according to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The structure and operation of preferred embodiments of the present invention will be described in detail below with reference to accompanying drawings.

FIG. 3 is an assembled perspective view of a heat exchanger according to an embodiment of the present invention, FIG. 4 is an exploded perspective view of the heat exchanger shown in FIG. 3, and FIG. 5 is a cross-sectional view showing heating water passages of the heat exchanger shown in FIG. 3.

A heat exchanger according to this embodiment includes a first end plate 110, a first subsidiary plate 130, a heat exchange device 200, a second end plate 310, and a second subsidiary plate 330. The first end plate is provided near an entrance through which heating water flows, and has a heating water inlet 120. The first subsidiary plate is fixed to the inner surface of the first end plate 110. The heat exchange device includes a plurality of heat exchange pipe units 210, 220, and 230 so that heat is exchanged between the heating water and combustion gas while heating water flows in the heat exchange pipe units through the heating water inlet 120. The second end plate has a heating water outlet 320 through which the heating water heated in the heat exchange device 200 is discharged. The second subsidiary plate is fixed between the inner surface of the second end plate 310 and the heat exchange device 200.

The first end plate 110 includes a flat part 110 a that closes one ends of the heat exchange pipes of the heat exchange device 200, and a bent part 110 b that is bent from the lower end of the flat part 110 a so as to make the heating water to flow therethrough. The heating water inlet 120 is formed at the bent part 110 b.

A plurality of pipe insertion holes 130 a and 330 a are formed through the first and second subsidiary plates 130 and 330 in a longitudinal direction thereof at regular intervals, respectively, so that both ends of the pipes of the heat exchange pipe units 210, 220, and 230 are inserted into the pipe insertion holes.

Combustion gas passages 201 are formed between the heat exchange pipes of the heat exchange device 200 so as to be spaced apart from each other at regular intervals so that combustion gas passes through the combustion gas passages.

In this embodiment, the cross-section of the heat exchange pipe is formed in a rectangular shape so that the surface area of the heat exchange pipe coming in contact with combustion gas is increased. However, the shape of the cross-section is not limited thereto, and any rectangular shape is possible as long as the heat exchange pipe has a rectangular cross-section of which a side coming in contact with the combustion gas has a width larger than the height. For example, each of the corners of the rectangular heat exchange pipe may have a rounded shape.

The heat exchange device 200 is provided with a first heat exchange pipe unit 210. The heating water, which flows from the heating water inlet 120 formed at one end of the heat exchange device, passes through the heat exchange pipe unit.

One ends of two heat exchange pipes 211 and 212 of the first heat exchange pipe unit 210 are inserted into the pipe insertion holes 130 a of the first subsidiary plate 130, and the other ends thereof are inserted into the pipe insertion holes 330 a of the second subsidiary plate 330.

The two heat exchange pipes 211 and 212 are spaced apart from each other at regular intervals so that combustion gas can pass therebetween.

In this case, the heat exchange pipe 211 is formed by bending a large metal plate so as to form a rectangular cross-section, caulking flanges 211 f protruding from the side surface, and fixing the flanges by brazing welding.

Flange insertion grooves 130 b and 330 b are formed in the pipe insertion holes 130 a and 330 a of the first and second subsidiary plates 130 and 330 so that the flanges 211 f of the heat exchange pipe 211 are inserted into the flange insertion grooves.

If the protruding flanges 211 f are removed by a separate process, the flange insertion grooves 130 b and 330 b do not need to be formed.

The two heat exchange pipes 211 and 212 are connected to each other at pipe connectors 211 a and 212 a that are formed at the other ends of the heat exchange pipes, so that the heating water in the lower heat exchange pipe 211 and the heating water in the upper heat exchange pipe 212 are sent to a second heat exchange pipe unit 220 through pipe connectors 212 b and 221 a.

The pipe connectors 211 a and 212 a protrude from the surface of the heat exchange pipe and are fixed to each other by welding. The shapes and fixing methods of pipe connectors 221 a, 221 b, 221 c, 222 a, 222 b, 222 c, 231 a, 231 b, and 232 a to be described below, where pipes of the second and third heat exchange pipe units 220 and 230 are connected to each other, are the same as described above.

According to this structure, since the distance between the two heat exchange pipes 211 and 212 can be decreased, it is possible to improve heat transfer efficiency. The structures of the second and third heat exchange pipe unit 220 and 230 to be described below are the same as described above.

One ends of two heat exchange pipes 221 and 222 of the second heat exchange pipe unit 220 are inserted into the pipe insertion holes 130 a of the first subsidiary plate 130, and the other ends thereof are inserted into the pipe insertion holes 330 a of the second subsidiary plate 330 so as to be disposed at regular intervals. The two heat exchange pipes 221 and 222 are connected to each other at pipe connectors 221 b and 222 a that are formed at one ends of the heat exchange pipes. While heating water sent from the first heat exchange pipe unit 210 is supplied to two heat exchange pipes 221 and 222 and sent to the left side, heat is exchanged between the heating water and combustion gas. Then, the heating water is sent to the third heat exchange pipe unit 230.

One ends of two heat exchange pipes 231 and 232 of the third heat exchange pipe unit 230 are inserted into the pipe insertion holes of the first subsidiary plate 130, and the other ends thereof are inserted into the pipe insertion holes of the second subsidiary plate 330 so as to be disposed at regular intervals. The two heat exchange pipes 231 and 232 are connected to each other at pipe connectors 231 b and 232 a that are formed at one ends of the heat exchange pipes. While heating water sent from the second heat exchange pipe unit 220 is supplied to two heat exchange pipes 231 and 232 and sent to the right side, heat is exchanged between the heating water and combustion gas. Then, the heating water is sent to places to be heated through the heating water outlet 320.

The second end plate 310 includes a flat part 310 a that closes one ends of the heat exchange pipes of the first and second heat exchange pipe units 210 and 220, and a bent part 310 b that is bent from the upper portion of the flat part 310 a so as to make the heating water to flow therethrough. The heating water outlet 320 is formed at the bent part 310 b.

A method of fixing the heat exchange pipes to the first subsidiary plate 130 and the first end plate 110, and a method of fixing the heat exchange pipes to the second subsidiary plate 330 and the second end plate 310 will be described.

Both ends of each heat exchange pipe are inserted into the pipe insertion holes 130 a of the first subsidiary plate 130, and then the first end plate 110 comes in close contact with the outer surface of the first subsidiary plate. Then, brazing welding is performed at portions where the heat exchange pipes and the pipe insertion holes 130 a of the first subsidiary plate 130 come in contact with each other (a in enlarged portion of FIG. 5) and at portions where the first subsidiary plate 130 and the first end plate 110 comes in contact with each other (b in enlarged portion of FIG. 5), thereby firmly fixing the pipes and the plates.

A method of fixing the heat exchange pipes to the second subsidiary plate 330 and the second end plate 310 also is the same as described above.

According to the above-mentioned structure, the heating water, which is sent to the right side through the first heat exchange pipe unit 210, is sent in opposite directions in the second and third heat exchange pipe units 220 and the 230. Therefore, the length of the flow passage through which heating water flows is increased, so that it is possible to improve heat transfer efficiency.

A structure where heating water flows from the left side of the heat exchange pipe to the right side thereof has been exemplified in the embodiment.

A structure where heating water flows from the lower side of the heat exchange pipe to the upper side thereof will be described with reference to FIGS. 6 and 7.

FIG. 6 is an assembled perspective view of a heat exchanger according to another embodiment of the present invention, and FIG. 7 is a cross-sectional view showing heating water passages of the heat exchanger shown in FIG. 6.

A heat exchanger according to this embodiment includes a heat exchange device 500.

The heat exchange device includes a plurality of heat exchange pipe units 510, 520, and 530 so that heat is exchanged between the heating water and combustion gas while heating water flows in the heat exchange pipe units through a heating water inlet 420 and the heating water is then discharged through a heating water outlet 620.

The heating water inlet 420 is formed on a lower heat exchange pipe 511 of a first heat exchange pipe unit 510, and the heating water outlet 620 is formed on an upper heat exchange pipe 532 of a third heat exchange pipe unit 530.

Like the embodiment shown in FIGS. 3 to 5, any rectangular shape is applied to each pipe of the heat exchange pipe units 510, 520, and 530 as long as the heat exchange pipe has a rectangular cross-section of which a side coming in contact with the combustion gas has a width large than the height.

Further, the pipe connectors, which connect the pipes of the heat exchange pipe units 510, 520, and 530, are the same as those of the embodiment shown in FIGS. 3 to 5 except for the positions thereof.

A first subsidiary plate 430 and a first end plate 410 are sequentially fixed to one ends of the heat exchange pipe units 510, 520, and 530, and a second subsidiary plate 630 and a second end plate 610 are sequentially fixed to the other ends of the heat exchange pipe units 510, 520, and 530.

Like the embodiment shown in FIGS. 3 to 5, pipe insertion holes 430 a and 630 a are formed through the first and second subsidiary plates 430 and 630, respectively. The pipe insertion holes 430 a and 630 a are spaced apart from each other in a longitudinal direction thereof at regular intervals, so that the distance between the heat exchange pipes is maintained constant.

The first and second end plates 410 and 610 are formed in a flat shape so as to close both ends of the heat exchange pipe units 510, 520, and 530.

The heat exchange device 500 is provided with the first heat exchange pipe unit 510 through which heating water flowing through the heating water inlet 420 passes. The first heat exchange pipe unit 510 includes two heat exchange pipes 511 and 512. The heat exchange pipes are fitted to the first and second subsidiary plates 430 and 630 and spaced apart from each other at regular intervals so that combustion gas can pass therebetween.

The heating water inlet 420 is connected to a pipe connector 511 a that is formed on the lower surface of the lower heat exchange pipe 511 of the first heat exchange pipe unit 510.

The two heat exchange pipes 511 and 512 are connected to each other at pipe connectors 511 b and 512 a that are formed at one ends of the heat exchange pipes. The heating water in the lower heat exchange pipe 511 and the heating water in an upper heat exchange pipe 512 are sent to the second heat exchange pipe unit 520.

The pipe connectors 511 a, 511 b, and 512 a protrude from the surface of the heat exchange pipes and are welded on the surface thereof, respectively. The shapes and fixing methods of pipe connectors (reference numerals are not given thereto) where pipes of the second and third heat exchange pipe units 520 and 530 are connected to each other are the same as described above.

The second heat exchange pipe unit 520 includes two heat exchange pipes 521 and 522, and the heating water in the second heat exchange pipe unit flows in a direction opposite to the direction of the flow of the heating water in the first heat exchange pipe unit 510, that is, flows to the left side.

The heating water passing through the second heat exchange pipe unit 520 flows into the third heat exchange pipe unit 530. The third heat exchange pipe unit 530 includes two heat exchange pipes 531 and 532. Heating water flows from left side to the right side, and is discharged through the heating water outlet 620 that is connected to the pipe connector formed on the upper surface of the upper heat exchange pipe 532.

FIG. 8 is a cross-sectional view of pipes of the heat exchange according to another embodiment of the present invention.

It is preferable that a distance between heat exchange pipes 711, 712, 713, 714, 715, and 716 through which combustion gas passes is larger at the entrance side 700 a as compared to that of at the exit side 700 b. That is, as shown in FIG. 8, the cross-section of each of the heat exchange pipes 711, 712, 713, 714, 715, and 716 has a trapezoid shape in a horizontal direction. Therefore, it can be seen that the distance between the heat exchange pipes 711, 712, 713, 714, 715, and 716 is decreased from the entrance side 700 a toward the exit side 700 b.

In general, the temperature of combustion gas is high at the entrance of the heat exchange pipe, and is low at the exit of the heat exchange pipe. Therefore, the volume of the combustion gas is reduced as the combustion gas comes to the exit of the heat exchange pipe. If the volume of the combustion gas is reduced as described above and the cross section area of the heat exchange pipe at the entrance is equal to the cross section area of the heat exchange pipe at the exit, the speed of the combustion gas is reduced, which cause the heat transfer efficiency to deteriorate.

Therefore, if the combustion gas flows into the entrance side 700 a having the large area and then flows out from the exit side 700 b like the structure of the heat exchange pipe of the present invention, it is possible to maintain the speed of the combustion gas from the entrance side 700 a to the exit side 700 b. As a result, it is possible to improve the heat transfer efficiency.

FIG. 9 is a cross-sectional view of pipes of the heat exchange according to another embodiment of the present invention.

As shown in FIG. 9A, a heat exchange pipe 811 may be formed by forming a flat plate in a substantially rectangular cross-sectional shape, making flanges 811 a come in contact with each other and protrude in a lateral direction, and fixing the flanges by caulking and brazing welding.

Further, in FIG. 9B, a heat exchange pipe 911 may be formed by forming a flat plate in a substantially rectangular cross-sectional shape, making flanges 911 a come in contact with each other so that both ends of a flat plate overlap each other on the upper surface of the heat exchange pipe 911, and fixing the flanges by caulking and brazing welding.

The present invention has been described above in connection with the exemplary embodiments of the present invention. However, the embodiments are illustrative, and it will be apparent to those skilled in the art that various modifications and changes may be made thereto without departing from the scope and spirit of the invention. 

1. A heat exchanger comprising: a heat exchange device including a plurality of heat exchange pipe units through which heating water passes and which are spaced apart from each other at regular intervals, the heat exchange pipe units being provided between a heating water inlet and a heating water outlet, and being formed of pipes having a rectangular cross-section of which a side coming in contact with the combustion gas has a width large than a height; first and second subsidiary plates to which both ends of the heat exchange pipe units are fixed to constantly maintain a distance between the plurality of heat exchange pipe units; and first and second end plates that are fixed to the outer surfaces of the first and second subsidiary plates, respectively.
 2. The heat exchanger according to claim 1, wherein pipe insertion holes are formed through the first and second subsidiary plates in a longitudinal direction of the first and second subsidiary plates, both ends of the plurality of heat exchange pipe units are fitted into the pipe insertion holes, and both ends of the heat exchange pipe units, first and second subsidiary plates, and first and second end plates are fixed by brazing welding, respectively.
 3. The heat exchanger according to claim 1, wherein the plurality of heat exchange pipe units forms a series of flow passages of which flow directions are alternately changed in opposite directions while the heating water, which flows from the heat exchange pipe unit provided at one end, flows to the heat exchange pipe unit provided at the other end.
 4. The heat exchanger according to claim 2, wherein the heating water inlet is formed through the first end plate, and the heating water outlet is formed through the second end plate.
 5. The heat exchanger according to claim 2, wherein the heating water inlet is formed at the heat exchange pipe unit into which heating water flows, and the heating water outlet is formed at the heat exchange pipe unit from which heating water flows.
 6. The heat exchanger according to claim 1, wherein the cross-sections of the plurality of heat exchange pipes are formed so that a distance between the heat exchange pipes at the entrance of the combustion gas is large and a distance between the heat exchange pipes at the exit of the combustion gas is small.
 7. The heat exchanger according to claim 3, wherein the heating water inlet is formed through the first end plate, and the heating water outlet is formed through the second end plate.
 8. The heat exchanger according to claim 3, wherein the heating water inlet is formed at the heat exchange pipe unit into which heating water flows, and the heating water outlet is formed at the heat exchange pipe unit from which heating water flows.
 9. The heat exchanger according to claim 2, wherein the cross-sections of the plurality of heat exchange pipes are formed so that a distance between the heat exchange pipes at the entrance of the combustion gas is large and a distance between the heat exchange pipes at the exit of the combustion gas is small.
 10. The heat exchanger according to claim 3, wherein the cross-sections of the plurality of heat exchange pipes are formed so that a distance between the heat exchange pipes at the entrance of the combustion gas is large and a distance between the heat exchange pipes at the exit of the combustion gas is small. 